1. FIELD OF INVENTION
The present invention relates to methods and equipment for blasting with abrasive media, and more particularly to a method and system for controlled abrasive blasting including an improved pneumatic valve system for remotely activating and modulating the flow of abrasive media from the apparatus's abrasive media holding tank. The invention also relates to air blasting equipment in that it provides a single apparatus capable of both air blasting and abrasive blasting.
2. BACKGROUND OF THE PRIOR ART
Blasting with abrasive media has a wide variety of applications. These include, but are not limited to, producing anchor patterns on surfaces prior to coating, removing old surface coatings and rust, surface finishing, deburring parts, metal removal, peening and stress relieving of parts, and providing surfaces with decorative "matte" finishes. Different operations will call for different abrasive materials varying in abrasiveness and particle size. Typical abrasives include aluminum oxide, sand, steel grit, garnet which are cutting abrasives, and shot, glass beads and nut shells which are non-cutting abrasives.
Conventional abrasive blasting systems are two pilot line systems having an "on-off" function only. That is, the operator has an "on-off" remote control handle which he grips to initiate blasting and which he releases to terminate blasting. The quantity of abrasive media which flows through the system is fixed and each time blasting is initiated or terminated the abrasive media holding tank must be pressurized or depressurized. Air blasting an abraded surface requires altogether separate air blasting equipment.
The present invention overcomes the many limitations of conventional blasting systems by providing an abrasive blast system which, in addition to having the usual "on-off" function, permits the operator to modulate or adjust the flow of abrasive media in accordance with the requirements of the blasting operation. The concept of the invention also permits the operator to air blast with the same equipment and to separately and remotely control pressurization and depressurization of the abrasive media holding tank. The highly versatile system of the present invention specifically contemplates the use of two unique cooperating control valves which have interchangeable and modular parts so that they can be adapted to varied system specifications.